This invention relates to a seat reclining apparatus, in particular to a seat reclining apparatus with a latch type lock structure.
This kind of seat reclining apparatus is provided with a pair of base plates secured to both sides of a seat cushion respectively. A pair of arms are pivotably supported by the base plates, a pair of upper teeth are secured to the arms, and a pair of lower teeth are pivotably supported by the base plates respectively. Each lower tooth engages and disengages the upper tooth by a operating member. These base plates, arms, upper teeth, lower teeth and operating members constitute a lock structure. The operating members are manipulated by operating an operating lever to lock and unlock the seat reclining apparatus.
In the seat reclining apparatus described above, the lock structure is located inside the base plates (seat cushion side) in order to increase the effective inner width of the seat cushion to the maximum. Upper rails constituting a seat slide structure are also located inside the base plates.
However, in the conventional seat reclining apparatus, the upper rail must be positioned sufficiently apart from the pivotal center of the lower tooth, in order to prevent the lower tooth from contacting the upper rail when the lower tooth pivots downward when the lock is released in the lock structure. Consequently, the base plate is enlarged to enlarge the seat reclining apparatus as a whole.
Moreover, the conventional seat reclining apparatus requires a rim portion to secure the upper rail to the base plate. For this reason, the base plate must be moved outwardly to increase the entire width of the seat. Consequently, it is difficult to set the base plate at predetermined setting position, so that the effective inner width of the seat cushion is reduced.
Further, in the conventional seat reclining apparatus, the tooth portion of the upper tooth is not covered, so that the tooth portion contacts the seat cushion, fouling it with oil supplied to the tooth portion.